Sodium phosphide

Sodium phosphide
Other names sodium phosphide, common trisodiophosphine
Identifiers
CAS number	12058-85-4
PubChem	61547
ChemSpider	55463 Y
Jmol-3D images	Image 1
SMILES [Na+].[Na+].[Na+].[PH6-3]
InChI InChI=1S/3Na.P/q3*+1;-3 Y Key: FHHBFSHDCCEUKM-UHFFFAOYSA-N Y InChI=1/3Na.P/q3*+1;-3 Key: FHHBFSHDCCEUKM-UHFFFAOYAE
Properties
Molecular formula	Na3P
Molar mass	99.943 g/mol
Appearance	black solid
Solubility in water	insoluble
Solubility	insoluble in liquid CO2
Structure
Crystal structure	hexagonal a = 4.9512 Å c = 8.7874 Å
Coordination geometry	around P 5 near neighbours, trigonal bipyramid [1]
Related compounds
Other anions	sodium chloride sodium nitride
Other cations	aluminium phosphide lithium phosphide
Y phosphide (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium phosphide, Na₃P, is a black, ionic salt containing the alkali metal sodium and the phosphide anion.^[2] Na₃P is a source of the highly reactive phosphide anion. It should not be confused with sodium phosphate, Na₃PO₄.

In addition to Na₃P, five other binary compositions of sodium and phosphorus are known: NaP, Na₃P₇, Na₃P₁₁, NaP₇, and NaP₁₅.^[3]

Properties

Like K₃P, solid Na₃P features pentacoordinate P centers.^[1] In the gas phase, molecular Na₃P and Li₃P are both trigonal pyramidal, with a lone pair of electrons on the central phosphorus atom.

Preparation

The first preparation of Na₃P was first reported in the mid-19th century. French researcher, Alexandre Baudrimont prepared sodium phosphide by reacting molten sodium with phosphorus pentachloride.^[4]

8 Na_(l) + PCl₅ → 5NaCl + Na₃P

Many different routes to Na₃P have been described. Due to its flammability and toxicity, Na₃P (and related salts) are generally prepared in situ. White phosphorus is reduced by sodium-potassium alloy to give the phosphide salt.^[5]

The conversion of white phosphorus to the phosphide has been well studied. Phosphorus reacts with sodium in an autoclave at 150 °C for 5 hours to produce Na₃P. ^[6]

P₄ + 12 Na → 4 Na₃P

Alternatively the reaction can be conducted at normal pressures but using a temperatures gradient to generate nonvolatile Na_xP phases (x < 3) that then react further with sodium.^[7] In some cases, an electron-transfer agent, such as naphthalene, is used. In such applications, the naphthalene forms the soluble radical anions and more rapidly reduces the phosphorus.^[8]

Uses

Sodium phosphide is a source of the highly reactive phosphide anion. The material is insoluble in all solvents but reacts as a slurry with acids and related electrophiles to give derivatives of the type PM₃:^[5]

Na₃P + 3 M+⁵ → M₃P (M = H, Me₃Si)

The trimethylsilyl derivative is volatile (b.p. 30-35 C @ 0.001 mm Hg) and soluble. It serves as a soluble equivalent to "P^3-".

Indium phosphide, a semiconductor arises by treating in-situ generated "sodium phosphide" with indium(III) chloride. In this process, the phosphide reagent is generated in situ from sodium metal and white phosphorus in N,N’-dimethylformamide, DMF.^[9]

Sodium phosphide is also employed commercially as a catalyst in conjunction with zinc phosphide and aluminium phosphide for polymer production. When Na₃P is removed from the ternary catalyst polymerization of propylene and 4-methyl-1-pentene is not effective.^{[10][citation needed]}

Precautions

Sodium phosphide is highly dangerous releasing toxic phosphine upon hydrolysis, a process that is so exothermic that fires result. The USDOT has forbidden the transportation of Na₃P on passenger aircraft, cargo only aircraft, and trains due to the potential fire and toxic hazards.[1]

References

1. ^ ^{a b} Dong, Y; Disalvo, F.J (2005). "Reinvestigation of Na₃P based on single-crystal data". Acta Crystallogr. E 61 (11): i223–i224. doi:10.1107/S1600536805031168. 
2. ^ Yunle, G; Fan, G; Yiate, Q; Huagui, Z; Ziping, Y (2002). "A solvothermal synthesis of ultra-fine iron phosphide". Mater. Res. Bull. 37 (6): 1101–1106. doi:10.1016/S0025-5408(02)00749-3. 
3. ^ Inorganic Chemistry, Egon Wiberg, Arnold Frederick Holleman Elsevier 2001 ISBN 0-12-352651-5
4. ^ Baudrimont. Ann. Chim. Phys. 1864, volume 2, 13.
5. ^ ^{a b} Gerd Becker, Helmut Schmidt, Gudrun Uhl “Tris(Trimethylsilyl)Phosphine and Lithium Bis(Trimethylsilyl)Phosphide.Bis-(Tetrahydrofuran)” Inorganic Syntheses, 1990, Volume 27, 243-249. doi:10.1002/9780470132586.ch48
6. ^ Xie, Y; Su, H; Li, B; Qian, Y (2000). "Solvothermal preparation of tin phosphide nanorods". Mater. Res. Bull. 35 (5): 675–680. doi:10.1016/S0025-5408(00)00263-4. 
7. ^ Jarvis, R.F; Jacubinas, R.M; Kaner, R.B (2000). "Self-Propagating Metathesis Routes to Metastable Group 4 Phosphides". Inorg. Chem. 39 (15): 3243–3246. doi:10.1021/ic000057m. PMID 11196860. 
8. ^ Peterson, D.J. 1967. Patent No. 3,397,039.
9. ^ Khanna, P.K; Eum, M.-S; Jun, K.-W; Baeg, J.-O; Seok, S. I (2003). "A novel synthesis of indium phosphide nanoparticles". Mater. Lett. 57 (30): 4617–4621. doi:10.1016/S0167-577X(03)00371-9. 
10. ^ Atarashi, Y.; Fukumoto, O. Japanese Patent No. JP 42,006,269.

External links

• Environmental Chemistry Chemical Database- safety information for sodium phosphide from the U.S. Code of Federal Regulations